ABC News(NEW YORK) -- Tennis phenom Cori "Coco" Gauff, appeared cool and calm as she took Wimbledon by storm, but she said Tuesday she was just as surprised as everyone that she became the star of the All England Club.

"This has all happened as a surprise," Gauff said on ABC News' Good Morning America. "I came into the tournament as a wild card into qualifying, and then to end up playing the No. 1 seed in qualifying, and then once I got through qualifying, playing my idol first round, this tournament has really been a roller coaster."

Gauff, 15, was ranked No. 313 in the world going into Wimbledon.

She became the youngest player to ever qualify for Wimbledon and defeated 39-year-old Venus Williams in straight sets in the first round. After beating Williams, she beat Magdaléna Rybáriková to reach the third round, where she faced Polona Hercog of Slovenia.

That match on Friday cemented her place in history, as she fought back from two match points, including a second set tiebreak, to come out on top. In doing so, Gauff became the youngest player to make it to the second week of Wimbledon since 1991.

"Being down those match points and then coming back, that was definitely a great feeling," said Gauff, who competed at Wimbledon while taking school tests.

Throughout her inspiring run, Gauff was supported by family, friends and strangers in her hometown of Delray Beach, Florida, who gathered at a local restaurant to watch her matches. She received support online from celebrities including from Beyoncé's mom, Tina Knowles, Jaden Smith and former first lady Michelle Obama.

Even so, Gauff said it was the cheering fans present at Wimbledon that stand out as her greatest memory from tournament.

"I think the most I'm going to remember is the crowd here," she said. "Ever since the first match they've been supporting me, even when I was down those match points they were supporting me, and even after I lost my match they were clapping for me."

"The people here have just been so kind and so amazing," she added.

Gauff's parents, Corey and Candi Gauff, also went viral during Wimbledon for their reactions to their daughter's incredible play.

Gauff said she always felt her parents' support both on and off the court.

"Their support means a lot to me," she said. "After the match, the first thing that came out of their mouths was that they were proud of me, even though I didn't play my best, but they were still proud of me that I fought as hard as I could."

Gauff is only allowed to play a limited number of pro tournaments due to her age. She said she hopes to play in the Citi Open in Washington, D.C., later this month. Fans can also catch her at the U.S. Open in August.